Isolation of Corynebacterium pilosum from a horse.

The research article discusses the successful isolation of a strain of bacterium, called Corynebacterium pilosum, from a horse’s urine as part of a study into previously undiagnosed urinary incontinence in the animal.

Background

• The study was prompted by understanding that the Corynebacterium renale bacterium was known to cause cystitis and pyelonephritis in various animal species, such as cattle, pigs, sheep, rabbits, and dogs. This, however, is the first time the Corynebacterium pilosum has been isolated from a horse’s urine.

The Affected Horse’s Condition

• The horse under the researchers’ investigation was a 4-year-old Thoroughbred gelding exhibiting symptoms of urinal incontinence for the prior six months.
• Tests on the horse’s urine showed increased specific gravity, pH, proteinuria, and heavy deposits of calcium carbonate crystals, but no evidence of leucocytes.

Isolation of Corynebacterium pilosum

• The bacterium was isolated using 5% sheep blood agar as the medium and incubated at 37°C for 48 hours.
• Colonies of Corynebacterium pilosum appeared after incubation in the form of yellow, circular, non-haemolytic colonies measuring 0.5 to 1mm in diameter.
• The bacterium was found to be nonmotile, aerobic and facultatively anaerobic. Electron microscopy revealed long pili, or hair-like structures on the bacterium.

Characteristics and Reaction Testing

• Tests on the bacterium showed it fermented glucose without gas production and produced acids from maltose, dextrin, trehalose, fructose, and mannose.
• The bacterium produced catalase, an enzyme that aids in breaking down hydrogen peroxide, and urease, which helps in nitrogen metabolism. It also reduced nitrate and hydrolyzed starch and hippurate.
• However, it failed to liquefy gelatin, utilize Malonate, produce indole, hydrogen sulphide; also, it did not hydrolyze Tween 80, deaminate phenylalanine, or decarboxylate lysine, arginine, and ornithine.

Further Isolation and Clinical Significance

• Further isolation attempts of Corynebacterium pilosum from the horse’s urine were successful, with the bacterium as the predominant organism, but Moraxella urethralis and Streptococcus were also isolated.
• Despite the successful isolation, the study was not able to conclusively point at the bacterium as the cause of the horse’s urinary incontinence, as there was no evidence of inflammation.